Multi-level magnetic recording has been used to increase areal density and to increase the capacity of hard disk drives (HDDs). In multi-level magnetic recording, servo pattern information as well as other supporting information is being stored in a dedicated servo layer (also called servo layer). The dedicated servo layer is separate from the dedicated data layer (also called data recording layer). The dedicated data layer is configured to store data.
The coercivity and nucleation field of the dedicated servo layer are required to be high enough such that information stored in the dedicated servo layer are not affected or deleted during writing to the dedicated data layer.